Detonating system

ABSTRACT

In the device disclosed an explosive pellet which releases a bomb lock on an aircraft is detonated remotely by applying an enabling pulse to a relay near the pellet and a second detonating pulse through a line to the pellet, which line is completed by the contact of the energized relay. Ground connections to the frame of the aircraft complete the detonator pulse circuit. Separate electrical lines actuate the relay and keep it floating in order to avoid the ground return.

fitted States Patent 1 1 3,922,943

Krehan cc. 2, 1975 DETONATING SYSTEM 2982180 5/1961 Hart 89/15 F 3319595 1967 V D 2]. 102 .2 R [75] Inventor: Friedrich Wilhelm Krehan, Munich,5 an Om at 1 HO Germany I Primary E.\'am1'nerStephen C. Bentley [73]Assigneez Messerschmltt-Bolkow-Blohm Assistant Jordan Mumch GermanyAttorney, Agent, or FirmToren, McGeady and 22 Filed: Mar. 25, 1974stanger [21] Appl, No.: 454,548

{57] ABSTRACT [30] Foreign Application Priority Data in the devicedisclosed an explosive pellet which re- M1111 29, 1973 Germany 2315704leases a bomb lock on an aircraft is detonated remotely by applying anenabling pulse to a relay near [52] U.S. Cl 89/15 F; 102/702 R thepellet and a econd detonating pulse through a line [51] Int. Cl. F42C15/12 to h ll t, hi h line is completed by the contact of Fleld 0fsealdlw 102/702 89/15 E, the energized relay. Ground connections to theframe 89/l-5 F of the aircraft complete the detonator pulse circuit.Separate electrical lines actuate the relay and keep it References Citedfloating in order to avoid the ground return.

UNITED STATES PATENTS 2,912,902 11/1959 Nessler 89/15 F 6 Clams 2 DrawmgFigures DETONATING SYSTEM BACKGROUND OF THE INVENTION This inventionrelates to means for setting off explosive detonators, and particularlyfor releasing a bomb lock.

Such bomb locks are released by electrically igniting a pyrotechniccartridge whose housing is grounded to the bomb lock by a metallicconnection that serves as a return line for electrical signals.

This type of bomb lock, which is used for dropping bombs, missiles, andsimilar payloads from bombcarrying aircraft, is shown for example in thepublication of the ML Aviation Company Ltd., Maidenhead, Berkshire,England, entitled Ejector Release Units, No. 119 Mk.1, No. 120 Mk.l,dated Dec. 1967. In such systems, undesired release of the payload isavoided by utilizing two autonomous jointly-necessary detonatingsignals. The detonating circuit includes a multi-wire arrangement and aso-called detonating pulse stepping switch. In the operating mode theswitch transmits the actual detonating pulse to the primer pellets ofpyrotechnic cartridges. If a single signal, that is, an undesired one,accidentally occurs at one of the input terminals of the detonatingpulse stepping switch, ignition does not follow.

In a simple embodiment, the detonating pulse stepping switch is a relaywhose operating contact closes an ignition line. The detonating signalsare generated at a command location remote from the stepping switch.Suitable grounds provide the return path for the signals.

Such systems have disadvantages. In particular, these circuits failtoprevent accidental ignition under all circumstances.

An object of this invention is to avoid these disadvantages.

Another object of the invention is to prevent uncontrolled dropping ofpayloads.

SUMMARY OF THE INVENTION According to a feature of the invention theseobjects are attained in whole or in part by bypassing the groundconnections in one of the two jointly necessary circuits and allowingone of the two circuits to float electrically either at the commandlocation or the stepping switch location.

Where the stepping switch is composed of a relay, one line carries anenabling pulse from the command location to the relay and a second linereturns the pulse to the command location so that the relay floatselectrically. This enables the stepping switch so that a detonatingpulse from the command location can pass to the explosive pellet.

The invention is based upon the recognition that, under certaincircumstances, undesired electrostatic charges which produce voltagedifferences of several hundred volts between ground connectionssuperimpose themselves on the switching level of the signals from thecommand locations to the detonating pulse stepping switch so thatignition pulses are simultaneous. This produces accidental release ofthe bomb lock and may destroy the ignition pulse stepping switchesand/or the ignition pulse generator. Such interference voltages mayoccur for example when lightning strikes the aircraft.

The invention overcomes the effect of such electrostatic charges becausecontrol lines free of this static are used for actuation of thedetonating pulse stepping switch. Thus static charges along the aircraftstructure, lightning bolts, and similar physical phenomena do not resultin any changes in the switching level of at least one of the signalinputs of the detonating pulse stepping switch. Thus undesired releaseof bombs, missiles. and similar explosive-carrying payloads or fuelcontainers is reliably avoided.

These and other features of the invention are pointed out in the claims.Other objects and advantages of the invention will become evident fromthe following detailed description when read in light of the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagramillustrating a circuit arrangement for releasing a bomb lock accordingto the prior art; and

FIG. 2 is a bomb lock releasing circuit embodying features of theinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS In the prior art circuitarrangement of FIG. 1, a grounded generator G having two input terminals2 and 3 is connected, via two lines 4'and 5, to a detonating pulsestepping switch ZF. A detonating explosive pellet Z connected to theoutput of the stepping switch ZF releases a bomb lock, not shown. Thelatter may be replaced by other types of detonatable devices such as apyrotechnic gas producer, a blasting stick, a rocket engine, or thelike. Within an aircraft, the generator G is remote from the steppingswitch ZF and the pellet Z.

Within the generator G a source S grounded to a metal portion of theaircraft applies current through the emitter-collector path of atransistor TRll, the line 4, a winding (also grounded to the metal ofthe aircraft at a point remote from the source ground) of a relay R, andthe return path through the metal grounds, when a first detonatingsignal is applied between the terminal 3 and ground. As a result thewinding of the relay R closes its contact rl. If a second detonatingsignal is applied between the terminal 2 and ground simultaneously withthe first detonating signal at the terminal 3, the source S suppliescurrent through a transistor TR2, the line 5, the contact r], the pelletZ, and the ground return connection to the source. The signals at theterminals 2 and 3 are generally in the form of pulses. The first signalbetween the terminal 3 and ground is an enabling pulse while the secondsignal between the terminal 2 and ground is the actual detonating pulse.The detonating pulse sets off the pellet Z.

The pellet Z opens the bomb lock or actuates any other type ofexplosively actuable device. Suitable circuits apply the voltagesbetween the terminal 2 and ground on the one hand, and the terminal 3and ground on the other hand. The two separate signals and the systemutilizing the two separate signals create an operation that preventsaccidental detonation However, it has been discovered that certainelectrical conditions may accidentally create sufficiently high voltagesbetween the ground points so as to cause accidental detonation of thepellet Z.

The circuit of FIG. 2 eliminates problems of this sort while retainingthe desired two-signal operation. In FIG. 2, suitable circuits similarto those of FIG. 1 apply the necessary pulse signals across the terminal3 and ground on the one hand and across the terminal 2 and ground on theother hand. Similarly the pellet Z is positioned to open a bomb lock orto actuate any other cxplosively operable device not shown. The circuitsfor applying the pulse signals at the terminals 2 and 3 are also notshown. The circuit of FlG. 2 corresponds to that of FIG. 1. However,here the winding of the relay R, instead of being grounded at the pelletlocation. is grounded through an electrically floating line 6 at theground point of the source S. Thus, a detonating pulse applied at theterminal 3 causes current to flow from the source S, through thetransistor TRl, through the line 4, through the winding of the relay R,through the line 6, and back to the source S without passing through themetal structure of the aircraft. If a pulse appears simultaneously atthe terminal 2, the source S simultaneously sends a detonating currentthrough the transistor TR2, the line 5, the contact r1 which has beenclosed by the current through the winding of the relay R, the pellet Z,and the ground return through the aircraft structure. This causesexplosion of the pellets Z and actuation of the bomb lock.

Interference voltages produced by lightning or similar charges can,therefore, no longer have any effect on line 4 or line 6. Thus,superposition of the control signals for the detonating pulse steppingswitch and an interference voltage can no longer take place. Release ofthe primer pellet Z by undesired interference signals can, therefore, nolonger occur.

The current flow description with respect to FIGS. 1 and 2 have forsimplicity been described as passing from the negative terminal ofsource S to the positive. For accuracy, this can be considered as anegative current flow.

Effectively the current through the relay R is an enabling current whilethe current through the contact rl is the actual detonating current.Nevertheless these can both be considered as simultaneously necessarydetonating signals.

What is claimed is:

I. A circuit arrangement for releasing a bomb lock of an aircraft.comprising an electrically ignitable primer cartridge for opening thebomb lock, said cartridge having a housing grounded to the aircraftstructure, an ignition line connected to the cartridge. a pair offloating leads, a command switch for generating a detonating pulse and arelay switching pulse, a relay having a winding and a contact saidcontact being connected to the ignition line, said winding beingconnected via the floating leads with the command switch, said commandswitch actuating said winding through said floating leads and passing anignition current through said ignition line. i

2. A control system for an explosively actuated device, comprising anelectrically actuable explosive detonator having a housing, a firstcircuit, a second circuit, said first circuit when enabled and whenactuated setting off said detonator, said second circuit when actuatedenabling said detonator. said detonator having a ground connection, saidfirst and second circuits having a command station grounded at a pointremote from the ground of said detonator, said circuits having aresponse portion located near said detonator, one of said circuitsconnecting the command portion and the response portion with floatingleads.

3. An apparatus as in claim 2, wherein said command portion includes apair of grounded pulse generators.

4. An apparatus as in claim 3, wherein said response portion includes aswitch system, said enabling circuit including the input of the switchsystem and said detonating circuit including the output of said switchsystem.

5. An apparatus as in claim 2, wherein said second circuit includes thefloating lines.

6. An apparatus as in claim 5, wherein said first circuit utilizes theground connections as a return.

1. A circuit arrangement for releasing a bomb lock of an aircraft,comprising an electrically ignitable primer cartridge for opening thebomb lock, said cartridge having a housing grounded to the aircraftstructure, an ignition line connected to the cartridge, a pair offloating leads, a command switch for generating a detonating pulse and arelay switching pulse, a relay having a winding and a contact saidcontact being connected to the ignition line, said winding beingconnected via the floating leads with the command switch, said commandswitch actuating said winding through said floating leads and passing anignition current through said ignition line.
 2. A control system for anexplosively actuated device, comprising an electrically actuableexplosive detonator having a housing, a first circuit, a second circuit,said first circuit when enabled and when actuated setting off saiddetonator, said second circuit when actuated enabling said detonator,said detonator having a ground connection, said first and secondcircuits having a command station grounded at a point remote from theground of said detonator, said circuits having a response portionlocated near said detonator, one of said circuits connecting the commandportion and the response portion with floating leads.
 3. An apparatus asin claim 2, wherein said command portion includes a pair of groundedpulse generators.
 4. An apparatus as in claim 3, wherein said responseportion includes a switch system, said enabling circuit including theinput of the switch system and said detonating circuit including theoutput of said switch system.
 5. An apparatus as in claim 2, whereinsaid second circuit includes the floating lines.
 6. An apparatus as inclaim 5, wherein said first circuit utilizes the ground connections as areturn.